My first pneumatic- 3/4" QEV with 5' blow gun barrel

[Kanonier]

My first pneumatic (completed a year ago)...

Components include:
- 3/4" QEV from McMaster Carr.
- Anderson aluminum camlock barrel coupling (reamed out with 3/4" drill and installed on barrel with JB Weld).
- 5' Long, .625 bore, black anodized aluminum barrel from a Cold Steel magnum blow gun.
- Picatinny rail for mounting a laser pointer sight (it's a front gas block from an AR-15 rifle that fits the .750" OD barrel perfectly).
- Brass 3/8" NPT fittings for triggering/filling, including a one way check next to the schrader valve.
- 300 PSI pressure gauge.
- Chamber is a stainless steel MSR backpacking fuel container with a 3/4" brass nipple. JB Weld was used when wrenching the nipple in as the threads were mismatched some. I have no idea what pressure this cylinder will hold and do not recommend it for your safety. I will retire this cylinder shortly as it's definitely the limiting factor of this design.

Projectiles include:
- All of the different .625 blowgun darts available from Cold Steel.
- I have found that some red electrician wire connectors fit this barrel perfectly. I remove the coil thread insert and drill and install an archery field point with epoxy. These fly very stable.
- Patched lead egg fishing sinkers.

[Cannoneer]

Ha!! another cannoneer!!! anyway nice launcher. It looks very sturdy and clean. I especially like the AR15 parts and the cam locks,but have you tried to use those broadhead darts? how was their accuracy? and what kind of pressure does this operate at?

[maverik94]

When I think that my .50 cal standard (lung-powered) blowgun will shoot wooden dowel darts 120+ ft at 180 fps and wire darts clean through 8" diameter plastic bottles filler with sand from 50' away, It makes me wonder what this gun will do. Nice, clean build. Yeah, replace that canister with something stronger and crank up the pressure!!!! Again, nice build, and good luck with any planned improvements!

[Kanonier]

Yes Cannoneer, Kanonier is Swiss (and also German) for Cannoneer.

Yes, I have tried the Cold Steel broadhead darts and they scratched the inside anodizing of the barrel. If I was to use them again, I would first dull the back edge of the broadhead with a grinder to prevent such. I didn't do any accuracy testing.

While on a closeout sale, I purchased a few packs of those archery, hunting, switchblade style broadheads to try on a short piece of aluminum arrow shaft with the electrician wire cap as a dart tail (modified on the lathe to hold the arrow shaft). I haven't tried them yet. I am thinking I will also need to turn a sabot out of Balsa or something to keep the switchblade broadhead centered in the barrel. They are expensive, but could be mean- can you imagine one traveling at 45 hardball speed (875 fps- much faster that your normal hunting arrow)? I don't know if broadheads would be NFA legal (without registration as a destructive device) if the bore was 1" or larger (judging from the flaming projectile letter), but they should definitely be legal with this .625 bore.

I looked and didn't see any rules about mentioning broadheads. I hope I haven't broken any Spudfiles rules.

I have been really impressed with how deep this gun will bury a lead egg fishing sinker into an old telephone pole.

I don't want to say what pressure I have used this chamber with, less people question my intelligence. I will comment about pressure after I swap in something safer for a chamber and purchase a chronograph.

[Gaderelguitarist]

I would think that your chamber is fine. A stainless steel bottle (how thick?) JB welded at its potentially weakest point. It could be safer, but then again I'm no real judge of that sort of thing.

I'd really like to see that blowgun pilot worked into son sort of handle. I personally never build a cannon that I can't fire like a gun (or a very large gun for that matter )

All in all though I have to say its very pleasing to look at, with no visible glue joints (this could be trick photography) and a nice "practical" look throughout.

Have you thought about mocking up a barrel support to fit between the chamber and barrel?

[velocity3x]

I like it! Very well done. My guess is that the tank will go higher but, you're wise not to push it without knowing it's actual limitations.

[Kanonier]

Gaderelguitarist, I agree with your thoughts about a handle (pistol grip) and barrel support. This gun was my first pneumatic effort. Rather that geek with this gun much anymore, I am planning such for the next build up. It will have a four-sided picatinny rail mount around the barrel, and the bottom rail section will mount a pistol grip with trigger. I think I found a pistol grip style air nozzle that I can modify for rail attachment. It has 3/8" NPT fittings instead of the smaller, more common 1/4" fittings. I plan to use a flexible pre-made 4,000 PSI hydraulic hose assembly instead of the current copper tubing to connect it back to the QEV.

I also plan to switch to the Humphrey made QEV (already in my possession) for the next build. I may hotrod it in some ways on the lathe, and measure performance changes with a chronograph before and after.

[jackssmirkingrevenge]

Extremely well made as far as first efforts go, the tank is slightly overkill in terms of volume if you're going for single shots but that's a minor thing Some damage pictures/videos are always appreciated

I don't want to say what pressure I have used this chamber with, less people question my intelligence.

Given the general level of lunacy on this forum, you're unlikely to be branded insane unless the thing actually blew up and the shrapnel actually killed someone

[Gaderelguitarist]

Well given that this was a prototype build, I can't wait for your next.

You've certainly started at a much more advanced level than most on this forum. I'm excited to see the kind of cannons you churn out.

[wyz2285]

nice chamber what's it made of?

[POLAND_SPUD]

read his first post

[watcher by night]

Kanonier,

since you are using the Cold Steel blowgun, if you want to make a pusher sabot for your .625 caliber, it's very easy to do using Cold Steel dart cones, as shown at this link: http://blowgun.lefora.com/2009/11/07/ne ... prototype/

As long as the Cold Steel darts are standing up to the pressures you're using, a sabot like the one shown probably will too.

I made the sabot and blowgun rig shown at the link for shooting subcaliber steel pellets. I placed the ring magnet attached to the outside of the blowgun barrel to hold the steel pellets in place within the barrel against the sabot. That way, once air pressure pushes the sabot and pellet far enough to be outside the magnet's field, there's nothing holding the sabot and pellet together, so they separate very cleanly.

I've used other types of magnets as well. If you want to use a magnet as shown, since you would be using much higher pressure than with a blowgun, you'd want to make sure the magnet wasn't so strong that the extra resistance caused the sabot to shatter from the air pressure--- the magnet very slightly delays the sabot/pellet from moving forward, and pressure builds a bit higher because of that. I doubt the sabot would break, but the possibility should be kept in mind. Also make sure the magnet is very firmly attached to the barrel, so that the attraction to the pellet doesn't jerk the magnet along with it!

Another thing that would enhance performance and lessen the likelihood of damage to the sabot would be to position the magnet so that it pulls the pellet all the way up into and centered within the socket of the forward cone of the sabot. On my blowgun, I used a crossbar to prevent the sabot from being pushed too far back by the magnet's pull on the pellet. For blowguns I also use asymmetric seating of the pellet against the sabot--sometimes using cut-down shotgun wads as sabots--, but at higher pressures that configuration might be overstressed. (But here's a look at it if anyone's curious: http://blowgun.lefora.com/2011/01/09/my ... oly-grail/ )

Here's another link: http://blowgun.lefora.com/2010/01/18/ea ... ke-sabots/ if you scroll down you can see using the sabot to launch multiple pellet loads, again using a magnet to keep them in loaded position pending launch.